Hi everyone,
 
The trusty Ford repair manual for a Mk2 Escort calls for 3% corrision inhibitor in water, which I presume to be a glycol type inhibitor. In the olden days I'd throw a can of Castrol Radiator Corrosion Inhibitor in, which was 200ml of green stuff in a rip top can (presumably glycol). I can't seem to find that on the shelf anymore, and modern long-life coolants specify minimum 33% concentration, which is big difference. So, I'm curious what everyone is using these days.
 
Thanks.

I am using demineralised water because a club member and my research confirmed that water is better at absorbing heat than coolant is. This is an important consideration in qld. I also use just a dash of green coolant because if there is a leak the telltale sign is there. If i lived in the high country of vic or canberra or had a alloy head things might be different.

I just use the normal green stuff at whatever ratio it says on the bottle. I have a 3 core radiator so need more water, have got a shroud and extra venting and airflow to the radiator, copes with FNQ temps and humidity ok. Lots of spruiking this waterless coolant going on, don't know how good it is, will probably take a little time before people get used to the idea or more information on it's efficiency. Len

I've been looking into various products, and learned the following:
 
Type A coolants include anti-freeze and anti-boil components (usually glycol), corrosion inhibitors and water.
Type B includes corrosion inhibitors and water.
 
I've always just used corrosion inhibitor (no need for anti-freeze where I live) so Type B will do me.
 
Here's where it gets a little interesting. Type B corrosion inhibitors are typically sold in small bottles (up to 1 litre) for use at low concentrations, e.g. Penrite RCI 100. This stuff is mixed with water at 5% concentration, and comprises 20-30% glycol, 10-20% sodium octanoate, 10mg/kg denatonium benzoate, and "other non-hazardous ingredients" making up the rest (probably water). A Mk2 Escort has a cooling system capacity of 7.1 litres, so assuming mid-range concentrations of each chemical, you'd end up with 89ml of glycol, 53ml of sodium octanoate, and about 3.6 grams of denatonium benzoate.
 
Compare that with Penrite's basic 350,000 km green coolant (Cool350), and which has >60% glycol, the same 10-20mg/kg denatonium benzoate as the RCI 100, and "other non-hazardous ingredients" making up the rest. This stuff is supposed to be used at a concentration range of 33-50% depending on how extreme the weather is. If you used this stuff at the 33% concentration range (only because it doesn't freeze much anywhere in Au) you'd end up with 1,406ml of glycol, and about 23 grams of denatonium benzoate.
 
So whether you use Type A or Type B coolant of the types above, there will be some glycol in it; only the concentration will vary (by a factor of nearly 16 in this example). If you don't need anti-freeze capability, then a lower concentration of glycol will evidently suffice. I wouldn't be surprised if the glycol is present only to act as a dye and bittering agent (to dissuade consumption). The same applies to the denatonium benzoate; about one seventh the concentration ends up in your system if you use RCI 100 in place of Cool350. The only uncertainty is whether there is any sodium octanoate in the Type A coolant. My somewhat educated guess is no, and that it is present in RCI 100 to compensate for the lower concentrations of other the remaining chemicals.
 
For my part, I think I'll just use what's left of the Type A glycol stuff I have on the shelf at 5% or more concentration before switching to something like RCI 100. The low dose of Castrol Radiator Corrosion Inhibitor I used for decades didn't seem to do any harm, and I see no reason to start using 33% glycol now seeing water has a higher specific heat capacity and better heat transfer efficiency than glycol mixes.

I tried Evans Waterless in my Pinto race car.  Didn't notice any difference from teh previous coolant.  Eventually Davies Craig informed me that Evans is NOT suitable for their electric water pumps so I drained it out ($300 learning exercise!).  I just use Penrite green concentrate and deminilarised water now.